Image based probe position and orientation detection

Abstract

An imaging system and method for determining sensor position and orientation with respect to an object having a known three dimensional structure is disclosed. The sensor acquires an image of the known structure. Position and orientation of the sensor is determined by processing the image with formulas corresponding to the known structure. One embodiment of the present invention comprises an ultrasound training system and method for determining the position and orientation of an ultrasound probe with respect to a known three dimensional structure embodied in an ultrasound phantom. The ultrasound probe acquires a cross sectional or partial volume image of the ultrasound phantom. The image is processed to obtain a number of geometrical image parameters. Position and orientation of the ultrasound probe are calculated from the image parameters using formulas based on the known three dimensional structure. The determination of probe position and orientation may be enhanced using image de-correlation techniques.

What is claimed is:  
     
       1. A method for determining a position and orientation of an ultrasound probe with respect to an ultrasound phantom in an ultrasound imaging system, the ultrasound phantom embodying a known structure and the ultrasound training system storing having a set of at least one predetermined geometric characteristic of the known structure, the method comprising: 
       acquiring an ultrasound image of said known structure;  
       processing the ultrasound image to obtain at least one image parameter; and  
       calculating at least one of probe position and probe orientation with respect to said phantom based on the at least one image parameter and the set of at least one predetermined geometric characteristic.  
     
     
       2. The method according to claim  1 , wherein the step of acquiring comprises: 
       acquiring a cross sectional image of the known structure.  
     
     
       3. The method according to claim  1 , wherein the step of acquiring comprises: 
       acquiring a partial volume image of the known structure.  
     
     
       4. The method according to claim  1 , wherein the step of calculating comprises calculating at least one of the probe position and orientation based on the known structure which comprises a number of planes of material embodied within said ultrasound phantom. 
     
     
       5. The method according to claim  4 , wherein the step of calculating comprises calculating at least one of the probe position and orientation based on the set of at least one predetermined geometric characteristic which includes a distance between at least two of said number of planes and an angle between at least two of said number of planes. 
     
     
       6. The method according to claim  4 , wherein the step of processing the image to obtain at least one image parameter includes measuring a distance between at least two of said number of planes and measuring an angle between at least one of said number of planes and a reference line associated with the focal axis of the probe. 
     
     
       7. The method according to claim  1  further comprising: 
       enhancing the calculation of probe position and orientation by performing image de-correlation to detect small changes in probe position and orientation.  
     
     
       8. The method according to claim  7  further comprising: 
       correcting for any error accumulations created by de-correlation by reevaluating the original calculation of probe position and orientation.  
     
     
       9. The method according to claim  1  further comprising: 
       selecting said known structure from a number of known structures and retrieving from memory the set of at least one geometric characteristic that corresponds to the selected known structure.  
     
     
       10. The method according to claim  1  further comprising: 
       displaying on a display the calculated probe position and orientation.  
     
     
       11. In an ultrasound training system having an ultrasound probe for acquiring images, a subsystem for determining a position and orientation of the ultrasound probe with respect to an ultrasound phantom, the ultrasound phantom embodying a known structure and the ultrasound training system storing a set of at least one predetermined geometric characteristic, the subsystem comprising: 
       an image processing module processing an acquired image of said known structure to obtain at least one image parameter; and  
       a computation module calculating at least one of the probe position and probe orientation with respect to said phantom based on the at least one image parameters and the set of predetermined geometric characteristics.  
     
     
       12. An ultrasound imaging system according to claim  11  further comprising: 
       a display displaying the calculated probe position and orientation.  
     
     
       13. An ultrasound imaging system according to claim  11  further comprising: 
       a memory storing said set of at least one predetermined geometric characteristic of said known structure.  
     
     
       14. An ultrasound imaging system according to claim  11 , wherein the known structure comprises a number of planes of material embodied within said ultrasound phantom. 
     
     
       15. An ultrasound imaging system according to claim  14 , wherein the set of at least one predetermined geometric characteristic includes a distance between at least two of said number of planes and an angle between at least two of said number of planes. 
     
     
       16. An ultrasound imaging system according to claim  14 , wherein the image processing module measures a distance between at least two of said number of planes and an angle between at least one of said number of planes and a reference line associated with the focal axis of the probe. 
     
     
       17. An ultrasound imaging system according to claim  11  further comprising: 
       an image de-correlation module enhancing the calculation of probe position and orientation by performing image de-correlation to detect small changes in probe position and orientation.  
     
     
       18. A method for determining a position and orientation of a sensor with respect to a phantom in an imaging training system, the phantom embodying a known structure and the training system storing a number of known geometric characteristics of the known structure, the method comprising: 
       acquiring with the sensor an image of said known structure;  
       processing the image to obtain a number of image parameters; and  
       calculating the sensor position and orientation with respect to said phantom using the image parameters and the known geometric characteristics.  
     
     
       19. The method according to claim  18 , further comprising: 
       displaying on a display the calculated sensor position and orientation.  
     
     
       20. The method according to claim  18 , wherein the step of acquiring comprises: 
       acquiring a cross sectional image of the known structure.  
     
     
       21. The method according to claim  18 , wherein the step of acquiring comprises: 
       acquiring a partial volume image of the known structure.  
     
     
       22. The method according to claim  18 , wherein the known structure comprises a number of planes of material embodied within said ultrasound phantom. 
     
     
       23. The method according to claim  22 , wherein the set of at least one predetermined geometric characteristic includes a distance between at least two of said number of planes and an angle between at least two of said number of planes. 
     
     
       24. The method according to claim  22 , wherein the step of processing the image includes measuring a distance between at least two of said number of planes and measuring an angle between at least one of said number of planes and a reference line associated with a focal axis of the sensor. 
     
     
       25. The method according to claim  18  further comprising: 
       enhancing the calculation of sensor position and orientation by performing image de-correlation to detect small changes in sensor position and orientation.  
     
     
       26. The method according to claim  25  further comprising: 
       correcting for any error accumulations created by de-correlation by reevaluating the original calculation of sensor position and orientation.  
     
     
       27. The method according to claim  18  further comprising: 
       selecting said known structure from a number of known structures and retrieving from memory the set of at least one predetermined geometric characteristic that corresponds to the selected known structure.